UI: Prevent user from starting ouputs while in settings

There's a loophole that would allow users to activate an output while in
the settings window via hotkeys -- this prevents that from being able to
happen.  Note that users can still shut down outputs, but they can no
longer start them up while in the settings window.

UI/window-basic-settings.cpp

@@ -277,6 +277,8 @@ OBSBasicSettings::OBSBasicSettings(QWidget *parent)
 
 	ui->setupUi(this);
 
+	main->EnableOutputs(false);
+
 	PopulateAACBitrates({ui->simpleOutputABitrate,
 			ui->advOutTrack1Bitrate, ui->advOutTrack2Bitrate,
 			ui->advOutTrack3Bitrate, ui->advOutTrack4Bitrate,
@@ -654,6 +656,11 @@ OBSBasicSettings::OBSBasicSettings(QWidget *parent)
 	UpdateAutomaticReplayBufferCheckboxes();
 }
 
+OBSBasicSettings::~OBSBasicSettings()
+{
+	main->EnableOutputs(true);
+}
+
 void OBSBasicSettings::SaveCombo(QComboBox *widget, const char *section,
 		const char *value)
 {